Field of the Invention
The present disclosure relates to a liquid discharge head that discharges a liquid and a liquid discharge device.
Description of the Related Art
As an example of a liquid discharge device for performing ink-jet recording, there is a liquid discharge device that supplies liquid from a separate liquid tank that contains a liquid (ink). In such a liquid discharge device, a liquid chamber that temporarily stores liquid supplied form the liquid tank is provided as a part of the liquid discharge head. Furthermore, in some cases, a remaining liquid amount detection mechanism for detecting the remaining amount of liquid stored inside the liquid chamber is provided in the liquid chamber.
As an example of the method of detecting the remaining amount of liquid, there is a so-called prism method in which a prism optical element is provided inside a liquid chamber, in which light for examination incident on the optical element is provided, and in which the intensity of the reflected light is detected to determine whether there is any liquid. However, there are cases in which the prism method fails to perform an accurate detection of the remaining amount when a liquid discharge of high flow rate in particular is performed and the liquid temporarily adheres and remains on the inner wall surfaces of the liquid chamber.
On the other hand, as another example of the remaining liquid amount detection mechanism, a so-called voltage application method is known in which a plurality of electrode pins are inserted in the liquid chamber and determination of whether there is any liquid is made by detecting the communication state between the electrode pins. In the voltage application method, electrical response changes greatly depending on whether or not the liquid is in contact with the two electrode pins at the same time. Accordingly, the method has an advantage in that detection of the remaining amount can be performed in a highly accurate manner even when a liquid discharge of high flow rate is performed.
For example, Japanese Patent Laid-Open No. 60-34870 sets forth two examples in which two electrode pins are inserted in a liquid chamber of a liquid discharge head mounted on a carriage and detection of the remaining amount of liquid is performed with the voltage application method. In the configuration illustrated in the first diagram, two electrode pins with different lengths are inserted towards the lower portion from an upper portion of the liquid chamber.
In the configuration illustrated in the second diagram of Japanese Patent Laid-Open No. 60-34870, one electrode pin is vertically inserted towards the lower portion from the upper portion of the liquid chamber and the other electrode pin is vertically inserted towards the upper portion from the lower portion. According to the configuration, the instance the electrode pin inserted from the upper portion is out of contact with a liquid surface (while the electrode pin inserted from the lower portion is continuously in contact with the liquid), determination is made that the remaining amount of liquid is small (no liquid). In the above configuration, whether there is any liquid or not is determined by whether there is, among the two electrode pins, an electrode pin (the electrode pin inserted from the upper portion of the liquid chamber) that is in contact with the liquid.
As disclosed in Japanese Patent Laid-Open No. 60-34870, by making the positions of the two electrode pins different in the height direction, the amount of liquid in the liquid chamber can be detected in a stepwise manner. In other words, from the point when one of the electrode pins becomes out of contact with the liquid, the electrical quantity flowing between the two electrode pins changes as the liquid surface gradually moves downwards. By measuring the change, detection of the liquid amount in a stepwise manner can be performed. Furthermore, by changing the length of the two electrode pins with respect to each other so that the distal ends thereof are not adjacent to each other, short circuiting between the electrode pins caused by the liquid connecting the distal ends of the two adjacent electrode pins (a bridged state) and erroneous determination that there is a large amount of remaining liquid being made can be restrained.